1.
Describe the bony structure of the foot, including its arches, subtalar and
transverse tarsal joints, and the bones and ligaments contributing to its
strength and flexibility. (W&B 644-652, TG3-40A, TG3-40B, TG3-41A, TG3-41B, TG3-61B)

Bones:

Images from "Anatomy of the Human
Body" by Henry Gray are provided by:

There are
7 tarsal bones, 5 metatarsal bones (the big toe is number 1, the little toe is
number 5), and 14 phalanges. The big toe has only 2 phalanges, proximal and
distal, while toes 2-5 each have 3, distal, middle, and proximal.

The tarsals have specific names, which you need to learn. The pictures above
will help, but working with the bones in your bone box will help much more. Starting posteriorly,
the bone you feel at the very back of your foot is the calcaneus, and on the
top of it you find the talus. The talus articulates with the calcaneus below,
the tibia and fibula above and on the sides, and the navicular bone in front.
Anterior to the navicular, you find the three cuneiforms, medial, intermediate,
and lateral. Finally, the cuboid bone is lateral to the cuneiforms,
articulating with the 4th and 5th metatarsals anteriorly, and the calcaneus
bone posteriorly. (Latin, cuneiform = wedge-shaped,
calcaneum = heel, navicula = boat)

Arches:

There are two longitudinal arches, medial and lateral. The higher medial arch
passes from the calcaneus to the talus to the navicular to the cuneiforms to
the metatarsals. They are supported by the plantar calcaneonavicular ligament
(spring ligament), and also by the tendons of the tibialis anterior and
tibialis posterior muscles. The transverse arch results from the shape
of the distal row of tarsal bones and the bases of the metatarsal bones.
Imagine an arch that goes over the top of the cunieforms and cuboid, and is
supported by the shape of the bones, various ligaments, and the tendons of the
fibularis longus, tibialis anterior, and tibialis posterior muscles.

Joints:

The subtalar joint is formed between the large concave facet on the under surface of the body of
the talus and the convex posterior articular surface on the superior aspect of
the calcaneus. A loose, thin walled articular capsule unites the two bones by
attaching to the margins of the articular surfaces. The transverse tarsal
joint is the designation for the irregular plane which extends from side to side
across the foot and is composed of the talonavicular articulation medially and the calcaneocuboid
joint laterally. This joint allows inversion and eversion of the foot.

Ligaments:

The plantar ligaments of the joints of the foot are very strong. They they are
supplemented by robust interosseous ligaments which keep the bones from
spreading apart. Notable on the sole of the foot are the long plantar
ligament and the plantar calcaneoucuboid and plantar calcaneonavicular ligaments. The elasticity of the
latter and its support of the head of the talus have led to it being called the
"spring ligament." The plantar aponeurosis may be likened to a
"tie rod" for the longitudinal arch, firmly connecting its ends and
preventing their spread.

We must also consider the extensor expansions. The three tendons of the
extensor digitorum brevis join the lateral sides of the tendons of the extensor
digitorum longus muscle to the second, third and fourth toes. These form the
extensor expansion on these digits.

Blood supply to these muscles is via the dorsalis pedis artery, which comes from the
anterior tibial artery.

The central compartment
also technically contains the tendons of the flexor digitorum longus muscle.
Also, note the split innervation of this compartment. Blood supply to the
flexor digitorum brevis muscle is from both the medial and lateral plantar
arteries,
while the quadratus plantae muscle only receives the lateral plantar artery. Adductor-interosseous
compartment:

adduct
digits 3-5 (move these digits toward the midline of the foot as defined by
the second digit),flex metacarpophalangeal and extend interphalangeal joints
of digits 3-5

deep
branch of lateral plantar nerve

The
adductor hallucis muscle receives blood from the plantar arterial arch, the plantar
interosseous muscles get plantar metatarsal arteries, and the dorsal
interosseous muscles get dorsal metatarsal arteries.
In summary, think about what you see as you take off the layers of the foot.
First, you are confronted with the plantar aponeurosis. As soon as you peel it
off, you see the flexor digitorum brevis muscle which runs from the calcaneus to
mid-sole, and then has 4 tendons that go to toes 2-5. If you reflect it, you
then see the flexor digitorum longus tendon and lateral to it is quadratus
plantae muscle. (The latter muscle helps longus flex the toes in a straight
line. Look at the tendon running from the medial malleous obliquely across the
sole. By itself it would flex the toes medially.) Reflect this layer, and you
see the adductor hallucis muscle. It is the one with both a transverse and an
oblique head. You will also see the interosseous muscles between the metatarsal
bones. The dorsal interosseous muscles abduct (DAB) the 2nd, 3rd, and 4th
toe. (Since the midline is the 2nd toe, one can abduct this toe in two
directions. Hence, it gets 2 muscles, one on either side, for abduction. The 3rd
and 4th toes each get one of these muscles, and because one wants to abduct the toes, the muscles
must be on the lateral side of the metatarsals. The big toe and the little toe
have their own abductors.) The plantar interosseous muscles adduct (PAD) the 3rd, 4th, and 5th
toes, i.e. pull them towards the second toe. (Therefore, these muscles must be
on medial side of the bone. The second toe's adduction occurs simply by
relaxing the abductors. The big toe has its own adductor muscle.)

4.
Identify the vascular supply of the foot and give the regions supplied by each.
(W&B 623-632, TG3-49, TG3-50, TG3-51)

The posterior tibial
artery divides into the medial and lateral plantar
arteries.
The medial plantar artery runs in the groove between the medial and central
compartments. It supplies the medial compartment, including the muscles of the
great toe. It also gives off most of the plantar digital branches. The lateral
plantar artery supplies the lateral compartment, including the muscles of the
little toe. Both the lateral and medial plantar arteries supply the central
compartment.

5. Identify
the nerves of the foot, and the muscles and cutaneous regions supplied by them,
so that given a functional and/or cutaneous loss one can predict the nerve and
the probable level of injury. (W&B 581, 621-622, TG3-49, TG3-50, TG3-51)

1.
List and describe the various types of moveable joints and give examples of
each type. (W&B 46-51)

The three
major types of joints, along with subtypes and examples, are listed here:

·Fibrous
joints: the most simple joints. They are only connected by fibrous ligaments. A suture is a fibrous joint that
eventually fuses, forming one bone from two (a synostosis), like in the skull
of a growing infant. A gomphosis is the joint between a tooth and the jaw. A syndesmosis is a fibrous membrane
or ligament that joins two bones. The tibia and fibula have an interosseous
ligament or membrane, as do the radius and ulna.

·Cartilaginous
joints: joined by cartilage only. These joints are avascular or anervous, except at
their margins. Synchondroses are temporary joints present in growing bones.
The epiphyseal plate (growth plate) will later ossify into solid bone. The
epiphysis has hyaline cartilage and the extension of ossification from the
diaphysis side converts it to bone. A symphysis is a permanent
cartilaginous union. They always have hyaline cartilage on the bony surfaces
concerned, and these cartilaginous surfaces are joined by fibrous tissue or
fibrocartilage.

·Synovial
joints: "diarthroses" (freely moveable joints). These joints are joined by a
fluid-filled capsule and accessory ligaments. Examples include the knee, ankle,
and hip.

2.
List the characteristics of and identify the parts of a typical synovial joint.
(W&B 47-49)

·Joint
capsule: a cavity, made of accessory ligaments, with synovial fluid inside. This
reinforces the synovial membrane.

·Synovial
membrane lining: secretes synovial fluid and covers the synovial cavity. It reaches to the edges
of the hyaline cartilage.

·Accessory
structures: accessory ligaments ("intracapsular" and "extracapsular");
articular discs or menisci, which are pads of fibrous cartilage; muscles and
tendons; and subsynovial fat.

Types of
synovial joints

·Plane: involves flat surfaces.
Movements consist of sliding of one surface on the other, and may be
multidirectional in one plane. Examples: facet
joints, joints of the tarsal bones of foot.

·Hinge
(ginglymus): movement around a single axis at right angles to the bone. Permits flexion and
extension only. These usually have strong collateral ligaments on each side
reinforcing the joint. Examples: elbow, knee.

·Pivot
(trochoid): rotary movement around a longitudinal axis. Rounded process of bone rotates
within a sleeve or ring composed of a bony fossa and a strong ligamentous band. Examples:atlas-axis,
radioulnar joint.

·Condyloid: oval surfaces allowing
movements in two planes at right angles to each other. Example:
radiocarpal joint

·Saddle
(sellar): movement in two basic axes, with circumduction. Example:
carpal-metacarpal joint of the thumb.

3.
Recall the movement characteristics of the various types of synovial joints.
(W&B 47-49)

See #2
above.

4-7??

Images from "Anatomy of the Human
Body" by Henry Gray are provided by:

Ankle
Joint: (TG3-60A, TG3-60B) The ankle joint is a hinge type of
synovial joint. It is located between the distal ends of the tibia and fibula and
the superior part of the talus. The distal ends of the tibia and fibula form a
deep socket into which the trochlea of the talus fits. (Latin, trochlea = block of pulleys, from Greek, trochos
= wheel) The tibia itself articulates with the talus in two places: the
inferior surface and medial malleolus of the tibia. The medial malleolus
grips the talus tightly during movements of the joint. This grip is strongest
during dorsiflexion because the anterior part of the talus is wider than the
posterior, and that wide section is forced into the joint. Plantar flexion is
relatively unstable and most injuries occur then. The lateral malleolus of the
fibula also articulates with the talus. The ankle joint has less range of
movement than the knee or the hip, so there are fewer supporting structures
needed. The fibrous capsule is supported on each side by strong collateral
ligaments The lateral ligament is composed of three parts:

·anterior
talofibular ligament: a flat, weak band

·posterior
talofibular ligament: a thick, fairly strong band

·calcaneofibular
ligament: a round cord

The medial ligament has
four parts, but you only need to know it as the deltoid ligament.It stabilizes the ankle
during eversion and prevents subluxation (partial dislocation) of the joint. (deltoid = shaped like a delta... the Greek letter)

8. Describe the blood
and nerve supply of the joints

·Ankle:

oBlood
Supply: derived from malleolar branches of the fibularartery and the anterior and posterior tibial
arteries

oNerve
supply: derived from the tibial nerve and the deep fibular nerve

9. Examine the
articulation between the talus and calcaneus (the subtalar joint) and study the
transverse tarsal joint, which is a complex joint that consists of the
talonavicular joint and the calcaneocuboid joint. What are their functions?

The
transverse tarsal joint refers to an irregular articular plane which extends
from side to side across the foot and is made of the talonavicular articulation
medially and the calcaneocuboid joints laterally. At this plane primarily, and
at other tarsal joints to a lesser degree, are produced the movements of
inversion and eversion of the foot. With inversion is the combined adduction
and plantar flexion; with eversion, abduction and dorsiflexion. The
contribution of the subtalar and talocalcaneonavicular joints is that of
movement around the axis that passes through the tarsal sinus. These movements
allow the foot to be placed firmly on slanting and irregular surfaces and still
serve as a firm basis of support for the body. (TG3-61)

10.
Identify the structure of the ankle and foot joints and describe how the joints
and ligaments provide firm footing but flexibility of movement. (W&B
642-652, TG3-60A, TG3-60B)

The
structure of the ankle joints have been described in #4 above. The following
are the structures of the foot joints, as described in the session on the foot:

Joints:

The subtalar joint is formed between the large concave facet on the under surface of the body of
the talus and the convex posterior articular surface on the superior aspect of
the calcaneus. A loose, thin walled articular capsule unites the two bones by
attaching to the margins of the articular surfaces. This joint allows the foot
to be placed firmly on slanting and irregular surfaces.The transverse tarsal
joint is the designation for the irregular plane which extends from side to side
across the foot and is composed of the talonavicular articulation medially and the calcaneocuboid
joint laterally. This joint allows inversion and eversion of the foot.

Ligaments:

The plantar ligaments of the joints of the foot are very strong. They are
supplemented by robust interosseous ligaments which keep the bones from
spreading apart. Notable on the sole of the foot are the long plantar
ligament and the plantar calcaneocuboid and plantar calcaneonavicular ligaments. The elasticity of the
latter and its support of the head of the talus have led to it being called the
"spring ligament." The plantar aponeurosis may be likened to a
"tie rod" for the longitudinal arch, firmly connecting its ends and
preventing their spread.

There are two longitudinal
arches,
medial and lateral. They pass from the calcaneus to the talus to the navicular
to the cuneiforms to the metatarsals. They are supported by the plantar
calcaneonavicular ligament (spring ligament), and also by the tendons of the
tibialis anterior and tibialis posterior muscles. The transverse arch results from the shape
of the distal row of tarsal bones and the bases of the metatarsal bones.
Imagine an arch that goes over the top of the cuneiforms and cuboid, and is
supported by the shape of the bones, various ligaments, and the tendons of the
fibularis longus, tibialis anterior, and tibialis posterior muscles.

Cultural enrichment: Check out
these sections from the 1918 version of Gray's Anatomy of the Human Body! Some of
the terms are (of course) out-of-date, but the illustrations are timeless.

10.
Does the anterior lateral malleolar artery communicate with the perforating
artery?

Yes. The
anterior lateral malleolar artery comes off the anterior tibial artery around
the ankle; it goes to the lateral malleolus. The fibular (peroneal) artery, off
the posterior tibial artery, gives off a perforating branch that passes forward
at the distal border of the interosseous membrane and anastomoses with the
anterior lateral malleolar artery. (TG3-38)

11.
Trace the deep fibular (peroneal) nerve into the anterior compartment of the
leg with its accompanying artery and vein. Note how it innervates anterior
compartment muscles and continues into the foot. What muscle does it supply
there? To what area does it supply cutaneous Innervation?

The deep
fibular nerve serves the tibialis anterior muscle, the extensor digitorum
longus muscle, the extensor hallucis longus muscle, and the fibularis
(peroneus) tertius muscle. It also provides articular branches to the
tibiofibular syndesmosis and the ankle joint. After crossing the ankle, the
deep fibular nerve divides into medial and lateral branches, which supply the
dorsum of the foot, and supplies the extensor digitorum brevis and extensor
hallucis brevis muscles. The medial branch divides into two dorsal digit
branches which supply adjacent sides of the first and second digits. Twigs also
go to the metatarsophalangeal and interphalangeal articulations of the great
toe and one to the first dorsal interosseous muscle. The lateral branch passes
laterally, deep to the extensor digitorum brevis muscle. It ends in an
enlargement from which branches distribute to this muscle, the tarsal joints,
and the three lateral intermetatarsal spaces for the supply of the periosteum
and the joints. The cutaneous innervation supplied by this nerve is on the
dorsum of the foot, between the second and big toe. (TG3-37)

14.
Define the axis of adduction and abduction in the foot and observe how each of
the plantar and dorsal interosseous muscles fits into the plan.

The axis
of abduction or adduction of digits of the foot is a line through the second
toe. (Note that, in the hand, the axis runs through the third finger.)

See #7 above.

15.
What is the plantar arterial arch?

The lateral plantar
artery, off of the posterior tibial artery, crosses the sole of the foot
diagonally from the medial to the lateral side. At the medial side of the base
of the 5th metatarsal bone, the artery turns medially around the margin of the
quadratus plantae muscle and sinks between the adductor hallucis and interosseous
muscles. It perforates the plantar interosseous fascia and passes medially
across the proximal ends of the second, third, and fourth metatarsal bones and
the corresponding interosseous muscles. Here it forms the plantar arterial
arch, anastamosing in the first interosseous space with the deep plantar branch
of the dorsalis pedis artery. (TG3-51)

21.
What contacts the articular (medial) surface of the lateral malleolus?

The medial
side of the lateral malleolus, which is part of the fibula, articulates with
the lateral surface of the talus.

22.
Note the iliopectineal bursa beneath the iliopsoas. Does it communicate with
the hip joint?

The
iliopectineal bursa lies between the iliopsoas muscle and the capsule. When the
capsule is perforated here, the bursa is open to the joint cavity.

30.
What does the transverse tibiofibular ligament do?

This
ligament helps to hold tibia and fibula together. It also forms a portion of
the articulation with talus.

31.
Relate the arrangements of the malleoli and ligaments to the prevalence of
ankle sprains.

Most ankle
sprains are caused by inversion of the foot, which causes tearing of the
lateral ligaments: the calcaneofibular and posterior talofibular ligaments.
Slight sprains might involve just partial tears, such as in the anterior
talofibular ligament. Sometimes the lateral malleolus can be avulsed off the
fibula or the fibula fractured if the ligaments are particularly strong. In
effect, the ligaments are stronger than the bone, and the bone often
"gives" first. The medial ligament is more rarely strained, but when
it is it is due to eversion of the foot.

32.
How is the stability of the ankle joint provided?

See #7 and
#10 above.

33.
Which position is most stable? Why this position?

Dorsiflexion
is more stable than plantarflexion. The talus is stabilized due to the wider
anterior side of the trochlea being immobilized by the tibial articulation. In
plantarflexion, the skinnier posterior side is articulating more and so more
movement is possible since it does not completely fill the space allowed the
anterior side.

34.
What muscles provide action of the ankle joint?

Dorsiflexion:
muscles of anterior compartment of leg. These include the tibialis anterior
muscle, the extensor hallucis longus muscle, the extensor digitorum longus
muscle, and the fibularis tertius muscle. When the foot is fully everted, it is
also fully dorsiflexed. (But remember, inversion and eversion are actions of
the foot itself.

Plantarflexion: muscles of posterior compartment of leg. These include the
tibialis posterior muscle, the flexor hallucis longus muscle, the flexor
digitorum longus muscle and the plantaris muscle. The lateral compartment also
participates in plantar flexion. (In fact, all muscles which enter the
foot behind the malleoli plantarflex the foot. When the foot is fully inverted, it
is also fully plantarflexed.

35.
What muscles provide stability of the ankle joint?

All of the
muscles mentioned above that cross the ankle lend stability to the ankle. The
ligaments provide the stability as well. See also #4 and #7 above.

36.
What is the function of the plantar ligaments dissected?

long
plantar ligament: maintains the arches of the foot and forms a tunnel for the
tendon of the fibularis longus by extending some of its fibers to the bases of
the metatarsals.

short plantar ligament: deep and medial to the long plantar ligament. It also
provides support of the longitudinal arch.

plantar calcaneonavicular (spring) ligament: highly elastic. It completes the
socket for the head of the talus bone on the medial side and provides springy
cushion for the foot. It also helps maintain the longitudinal arch of the foot.
(TG3-61A)

37.
What are the actions of the subtalar articulation?

This joint
is pretty stiff, though it allows some inversion and eversion.

This
ligament is located inside the tarsal sinus. It is a strong band which connects
the adjacent surfaces of the talus and the calcaneus along the oblique tarsal
grooves. It provides support for the subtalar joint. (TG3-60B)

40.
What are the two parts and the action of the transverse tarsal joint?

It is
formed by the combined talonavicular and calcaneocuboid joints. The two
separate joints align transversely. (Transection across the transverse tarsal
joint is a standard method for surgical amputation of the foot.)

Inversion and eversion take place primarily through the transverse tarsal
joint.
(TG3-61B).

41.
What are the actions of the foot?

Dorsiflexion, plantar
flexion, inversion and eversion of the foot are the main actions of the foot.